Process of making pressure sensitive record material



Patented Apr. 25, lhfiii BitTE-Mt -OF- F-ECE PROCESSOF MAKING PRES SURESENSITIVE RECORD MATERIAL Barrett liLGreen, Dayton, Ohio, assignor to The National Cash Register Gompany, Dayton, Ohio, a corporation of Maryland No Drawing. Original application November 8,

.1947, Serial No. 784,939. Divided and this application December 2, 1948, Serial'No. 63',217

.2 Claims.

This invention relates to improvements in process of making apressure-sensitive record material. This application is a division of the pending application of Barrett K. Green, Se-

' rial No. 784,939, filed November 8, 1947, for Process of making pressure-sensitive recordmaterial.

The principal object of this invention is to provide a process of making a pressure sensitive record material, on which 'a mark of distinctive color may be produced-by the mere application of localized pressure, and which is not subject to the disadvantages inherent in the pressuresensitive record material disclosed in United States Letters Patent No. 2,299,693, patented October 20, 1942, on the application filed by Ban rett K. Green on'February 23, 1946. That patent disclosesa pressure-sensitive record material including the combination of an insulating medium, a rupturable solid material such as gum dammar, having included therein, interspersed droplets of a plurality of liquid reagents, which are chemically reactive to produce a distinctive color in the record material at the points of application of localized'pressure thereto, such'pressure rupturing the insulating medium to permit chemical reaction between the two liquid-reagents. The two reagents disclosed in thispatent are gallic acid and ferric ammoniumsulphate, each dissolved in glycerine. These-reagents are ionized by the'glycerine, which con-"1 1.:

stitutes an ionizing'medium, andthechemical reaction proceeds by interchange of ions when the two solutions are allowed to mix, upon the rupture of theinsulating medium, Thereaction disclosed in that patent depends uponthe presence of the reagents in an ionizing'medium. However, any available ionizing medium is bygroscopic, with the result thattherecord material, made in accordance with this patent, is

sensitive to an excess of moisture, and conditions= of high humidity may cause the insulating medium to cease to be effective, with the result that the chemical reaction takes place without any application of localized pressure, and the record material is stained and discolored, so that it ceases to be useful.

As stated above, theprincipal object of the present invention is to provide a process of makf ingapressure-sensitive record'material that is *not" subject to'the defects and'disadvantagcs of that disclosed in'Patent No. 2,299'1693yas ind-icated above.

Another object of the present invention isto provide a process of makinga recordmatezdal upon which a mark of distinctive color may be produced, at the, points of applicationof localized pressure thereto, by such mere application of localized pressure, and which will notbecome dis colored or staineddue to. the efiectof light, at

mospheric conditions, or'aging.

2 In short, it is 'theobject .:of this invention to'provide a processof making a pressure-sensitive record material in'which the mark of distinctive color will berproduced only at the points of application-of localized pressure, and at no other points, and underano'other conditions.

Another object of this invention is to provide a process ofmaking a pressure-sensitive"record material in which the markioi'. distinctive color is produced by the chemical reactionof colorforniihg reactants, in'the absence of any liquid ionizing medium therefor.

'A further object of thislinvention is to proride a process of making a pressure-sensitive record material in which a mark of distinctive color is produced by a-reaction between solid'particles of color forming reactants.

Further objects, and obje'cts' relating to details and economies of operation, will definitely appear from the detailed-description to follow.

The objects of'this invention have been attained by the several embodiments thereof described indetail in thefollowing' specifications. This invention' is clearly defined andpointed out in the appended claims.

In general, the present invention contemplates a process of making a pressure-sensitive record :sulating medium 'is ruptured at the points of ap- -.:plication of said localized pressure, and such rupture permits color-forming reaction contact betweenthe reactants at such points, in the absence of anyiiquidionizing medium for said reactants. 'Theire'sult islthat a mark of distinctive 'c'olor is produced by the mere application of lo- 'c'a 'lized' pressure.

"-The' color reactionemployed is of: the,:so-called,

adsorptiontype' wherein an inorganic compound causes a color change in'a-n rorganicfcompound ccmingin'tc contact therewith.

0f the reactantmaterials employed the organic 'material is an electron donor aromatic com- "pound having' 'a double bond'system which is convertible to "a; more highly'polarized conjugated form upon taking part in an electron acceptor-donor solid surface chemical reaction, giving it a distinctive color, and the inorganic fmaterial is*a"material--whichis an acid relative ""td'the organic'materiaL so' as to be an electron acceptor when in adsorption contact therewith. Both materials are in fine particle form in order to furnish a large reactant surface area per unit area of the record material which enhances the depth of color per unit area of the record material.

According to one embodiment of the invention, solid particles of one of the color-forming reactants are carried by and dispersed in a solid insulating medium, to which a coating of solid particles of another color-forming reactant is applied. In this case, the application of localized pressure ruptures the solid insulating medium, at the points of application of such pressure, and brings about color-forming reaction contact between the solid particles of color-forming reactants at such points, thus producing the mark of distinctive color. Preferably, this pressure-sew sitive record material includes a base web, such as a fibrous web of paper or the like, to which the coating of solid insulating medium and the colorforming reactants is applied.

The insulating medium is a pressure-rupturable film derived from an organic film-forming hydrophilic colloid substance.

Since it is difficult to show precisely the spatial relationship between the solid particles of colorforming reactants, the solid insulating medium, and the base web, it is preferred not to attempt to illustrate any embodiment of this invention by drawings.

In the following examples, there will be described embodiments of this invention, by means of which the objects of the invention have been successfully attained.

A preferred embodiment of this invention produces a pressure-sensitive record material consisting of a web of paper having applied thereto a coating including casein as the solid insulating medium and solid particles of two color-forming reactants; namely, kaolin and the compound 201,4 bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid, having the structural formula U aM In this embodiment, casein constitutes the solid insulat ng medium, insulating the solid particles of kaolin and the compound 2(4A bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid from color-forming reaction contact with each other. The record material is normally white, and the application of local zed pressure thereto ruptures the solid insulating medium at the points of application of Such pressure, permitting color-forming reaction contact between the solid particles of the reactants, pro ducing a dark blue mark.

The compound 2(4A bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid, above referred to, is described and claimed in the pending application of Clyde S. Adams, Serial No. 599,968, filed June 16, 1945, now Patent No. 2,458,328, for 2&4 bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid.

This record material has been successfully produced, in accordance with this embodiment of the invention, by first coating a web of paper with a 1 being about ten to one.

casein solution having solid particles of kaolin dispersed therein, the ratio of kaolin to casein This coating having been dried, the coated side of the paper was treated with a 3% by weight solution of the compound 2(l,4' bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid in ethyl alcohol. The excess of solution was removed, and the treated paper was then dried to evaporate the solvent.

When these ingredients are applied to the paper as a coating thereon, such coating should weigh about .0028 pound per square foot of surface and should have a thickness of the order of from .0005 to .001 inch. The thickness of the coating varies, of course, with the treatment to which the record material is subjected in finishing. The solid particles of kaolin in this record material may be of about the order of ten microns in diameter, although considerable variation in particle size is possible without any ill effects. Particle size of the benzoic acid material is largely determined by the method of application of that ingredient. The particles of these reactants may be as large as ten microns in diameter and frequently are much smaller.

Other organic film-forming hydrophilic colloid substances such as gelatin, methyl cellulose, starch, polyvinyl alcohol, and animal glue are representative materials that may be substituted for casein as the solid insulating medium. Any of the following inorganic materials may be substituted for kaolin as one of the color-forming reactants: attapulgite (Attapulgus clay), talc, bentonite, halloysite, and magnesium trisilicate. When any of these materials are substituted for the kaolin in this combination, the resulting record material will be white or bluish white in color, and a dark blue mark will appear thereon as the result of the application of localized pres sure.

A method that has been used successfully to make the pressure-sensitive record material described above is as follows: A slurry of kaolin and water was prepared including fifty parts by weight of kaolin to fifty parts by weight of water, and a small amount of a suitable dispersing agent, such as sodium metaphosphate, for instance, in the proportion of 0.075% by weight was added to facilitate the dispersion of the particles of kaolin throughout the slurry. The addition of this dispersing agent reduces the viscosity of the slurry considerably, thus facilitating its mixing and appl cation, and also preventing the settling of the solid particles of kaolin. A 25% by weight solution of casein in water was formed by first, dispersing the casein in cold water by stirring for fifteen minutes at room temperature and, then, heating up to 60 degrees centigrade. Five parts by weight of a 28% ammonium hydroxde solution--that is, one having a specific gravity of 25.9 B., at

-Were then added to the hot casein solution,

' which was stirred for about fifteen minutes and allowed to cool to room temperature. The kaolin slurry and the alkaline casein solution were then thoroughly mixed and blended, in the ratio of ten parts by weight of kaolin to one part of casein, and, at this stage, a small percentage for instance, about 0.05% by weightof a solution of equal parts by weight of tributyl phosphate in alcohol, or other anti-foaming agent, was added. This mixture of the kaolin slurry and the casein solution was then applied as a coating to the paper, and the coated paper was dried and calendered or treated in any des re: way to give the proper surface finish. A solution in toluene of about 3% by weight of the benzoic acid material was then applied to the coated side of the paper, the excess or" this solution was removed in any suitable way, as by passing under a doctor blade, and then the treated paper was dried to evaporate the toluene, and was ready for use.

The pressure-sensitive record materials d sclosed herein are not claimed in this application but are disclosed and claimed in the pending application of Barrett K. Green, Serial No. 784,939, filed November 8, 1947, for Pressuresens tive record material, and in a divisional application, Serial No. 59,428, filed November 10, 1948.

It is understood that the process of making a pressure-sens tive record material described herein is susceptible of considerable variation without departing from the spirit of the invention.

What is claimed is:

1. The process of making a pressure-sensitive record material including the forming on a supporting member a film-like deposit of solid particles of a plurality of adsorpt on color-forming reactants disposed in contiguity with each other and a solid insulating medium, derived from an organic film-forming hydrophilic colloid substance, insulating said reactant particles from color-forming reaction with each other, at least one of said reactants being an inorganic compound and at least another of said reactants being an organic compound adsorbable therewith, and said reactants being so selected as to react, in the absence of a liquid ionizing medium for the reactants, to form a distinctive color when brought into adsorption contact with each other, one of the color-forming reactants being the compound 201,4 bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid, having the structure worm? and the inorganic reactant being in fine particle form providing a large adsorbent surface area and which is an acid relative to the organic reactant so as to be an electron acceptor when in adsorption contact with said organic reactant.

2. The process of making a pressure-sensitive record material including the steps of coating a supporting member with a film of solid insulating material, derived from an organic film-forming hydrophillc colloid substance, having particles of a first color-forming solid reactant dispersed therein, and depositing on said film particles of a second color-forming solid reactant, one of said reactants being an inorganic compound and the other of said reactants being an organic compound adsorbable therewith, and said reactants being so selected as to form a distinctive color when brought into contact with each other, and said solid insulating material being such as to insulate the reactants from color-forming reaction contact with each other, the second colorforming reactant being the compound 2(4,4' bis dimethylaminobenzohydryl) 5 dimethylaminobenzoic acid, having the structure (0 nommore),

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Country Date Great Britain Jan. 4, 1943 Number 

1. THE PROCESS OF MAKING A PRESURE-SENSITIVE RECORD MATERIAL INCLUDING THE FORMING ON A SUPPORTING MEMBER A FILM-LIKE DEPOSIT OF SOLID PARTICLES AT A PLURALITY OF ADSORPTION COLOR-FORMING REACTANTS DISPOSED IN CONTIGUITY WITH EACH OTHER AND A SOLID INSULATING MEDIUM, DERIVED FROM AN ORGANIC FIM-FORMING HYDROPHILIC COLLOID SUBSTANCE, INSULATING SAID REACTANT PARTICLES FROM COLOR-FORMING REACTION WITH EACH OTHER, AT LEAST ONE OF SAID REACTANTS BEING AN INORGANIC COMPOUND AND AT LEAST ANOTHER OF SAID REACTANTS BEING AN ORGANIC COMPOUND ADSORBABLE THEREWITH, AND SAID REACTANTS BEING SO SELECTED AS TO REACT, IN THE ABSENCE OF A LIQUID IONIZING MEDIUM FOR THE REACTANTS TO FORM A DISTINCTIVE COLOR WHEN BROUGHT INTO ADSORPTION CONTACT WITH EACH OTHER, ONE OF THE COLOR-FORMING REACTANTS BEING THE COMPOUND 2(4,4'' BIS DIMETHYLAMINOBENZCHYDRYL) 5 DIMETHYLAMINOBENZOIC ACID, HAVING THE STRUCTURE 